Snares, baskets, and graspers are in widespread use for severing capturing and retrieving tissue specimens and foreign bodies from within subjects. The devices are used in human and animal subjects, in laparoscopic surgeries and other procedures where access within a subject is only possible via a small opening. One exemplary use is for cutting off and retrieving intestinal polyps where a wire snare, passed through an colonoscope instrument channel, encircles and is tightened about an intestinal polyp to sever the polyp. The severed polyp is retrieved in a net inserted through the instrument channel. The net is manipulated to enclose the polyp and then withdrawn with the instrument so that the tissue architecture remains undisturbed.
In this procedure, as well as others, the net and snare must be quite compact in order to pass into the subject through the instrument channel, or other passage. Prior art proposals have employed snares supported within plastic tubes that were snaked into the subject to locate the snare where desired. The snare was then deployed from its tube, manipulated to cut off the polyp and retrieved into the tube for removal from the subject.
A net, collapsed within another tube, was introduced through the instrument channel, etc., for removing the polyp. When near a target polyp, the net was deployed, like the snare, and manipulated to net the polyp. The net was then closed sufficiently to secure the polyp and withdrawn from the subject.
U.S. Pat. No. 5,643,283 to Younker, which is incorporated herein by reference in its entirety, discloses a device for retrieving an object from within a subject. The device comprises a shaft and a compressible pouch for receiving the object positioned adjacent a distal end of the shaft. The pouch includes a mouth which can be opened and closed. The pouch is retained, in proximity to the distal end of the shaft, on a cable loop by a slidable tether. The net is free to slide on the cable loop to form a pouch at the distal end of the shaft. The tether is fixed at a second location near the proximal end of the shaft, and in one embodiment, is tied off to a ring and secured with heat shrink tubing. When the targeted foreign object is within the pouch, a clinician disengages the ring portion of the handle to close the net around the object. The clinician then removes the device from the patient and unloads the object from the net. The clinician then places the ring on a post, in order to pack the pouch into the distal end of the shaft.
In operation of a commercial embodiment of U.S. Pat. No. 5,643,283, several problematic issues have surfaced. Clinicians have experienced difficulty in understanding the operation of the tether, in particular, the interaction of the ring and post. The ring is to be used to pull the net inside the shaft only when an object is not within the net. In preparation to capture an object, the ring should be disengaged to release the net. The net is then slid over the targeted object and the net is closed. At this point, proper operation would involve merely removing the device from the patient. However, some clinicians when operating the device try to further pull the net inside the shaft when the net is bundled up at distal end of cable loop. This will cause the net to jam, or in some cases, damages the tubing. The occasional improper operation of the device sometimes causes permanent malfunction.
The commercial embodiment discussed above also adds undesirable expense to the product. Specifically, the full length tether and heat shrink operation add material cost and labor assembly cost to the device.
The present invention provides a new and improved retrieval device that is so constructed and arranged that net movement during deployment and retrieval is not prohibitively restricted. Secure net attachment is assured and that provides for convenient net packing in the introducer passage. The device provides a convenient and economical method of sample retrieval during endoscopic procedures. The new retrieval device is easy assemble, manufactured at a reduced cost, and easier to use by the end consumer.